Causes

Dental implants are life-changing but not risk-free. Knowing what causes failure can help you avoid pain, infection, and expensive retreatment.
Most dental implants succeed long term, but failure still occurs in up to 20- to 40% of cases.
Dental implant failures can be categorized by timing (early vs. late failure) and by cause (biological, mechanical, or iatrogenic). Here's a structured overview:

Occurs within the first weeks to months after placement, often due to:

Poor Bone Quality or Quantity
- Inadequate bone volume for stability
- Low bone density (e.g., in the posterior maxilla)
Surgical Trauma
- Overheating the bone during drilling
- Excessive compression of cortical bone
Contamination or Infection
- Bacterial contamination at the time of placement
- Poor aseptic technique
Micromovement of the Implant
- Lack of primary stability
- Premature loading or patient non-compliance
Systemic Health Issues
- Uncontrolled diabetes
- Smoking
- Immunosuppression or chemotherapy
Medication-Related Complications
- Bisphosphonates
- SSRIs or PPIs (possible effects on bone healing)

Occurs months to years later, often due to:

Peri-Implant Mucositis
- Inflammation of soft tissues around the implant
- Usually reversible with good oral hygiene
Peri-Implantitis
- Progressive bone loss with inflammation
- Caused by plaque accumulation and pathogenic biofilm
- May be accelerated by poor prosthetic design or cement remnants
Excessive Occlusal Forces / Bruxism
- Overloading of the implant
- Lack of occlusal adjustment or protective appliances
Poor Prosthetic Planning or Execution
- Misaligned implants
- Ill-fitting abutments or restorations
- Cement left in peri-implant sulcus (if not screw-retained)
Inadequate Maintenance
- Lack of patient compliance with hygiene and recalls
- No regular professional cleaning or monitoring
Mechanical Failures
- Fractured implant, screw, or abutment
- Loosening of components

These are failures resulting from the clinician’s technique or decision-making: